Hydrogen-Bonded Organic Framework Nanosheet-Modulated Polymer/Filter Paper Composite Janus Separator for Aqueous Zinc-Ion Battery

Abstract

Aqueous zinc-ion batteries (AZIBs), recognized for their high safety, theoretical capacity, and environmental benignity, are considered ideal candidates for large-scale energy storage. However, issues such as zinc dendrite formation and uncontrolled side reactions at the zinc anode impede their practical application. Traditional separators are costly, bulky, and ineffective at inhibiting zinc dendrite growth. We developed a filter paper (FP)-based Janus separator (FP-HOFs) utilizing hydrogen-bonded organic frameworks (HOFs) nanosheets assembled via hydrogen bonding. The unique hydrogen-bonding framework of HOFs, enriched with functional groups, can attract Zn²⁺, immobilize the surrounding solvated ions, facilitate desolation, accelerate zinc deposition kinetics, and regulate the separator's surface pore structure to uniformly distribute ionic flux, thereby preventing zinc dendrite formation. In batteries assembled with FP-HOFs separators, the zinc anode demonstrated stable charge/discharge performance for more than 500 h at a current density of 2.5 mA cm⁻², with a high coulombic efficiency of 99.0% after 2000 cycles at the same current density and low nucleation overpotential. Zn||V₂O₅ batteries incorporating FP-HOFs separator exhibited superior cyclic capacity and stability, reaching a maximum capacity of 271.9 mAh g⁻¹ at a current density of 3 A g⁻¹, which is 1.37 times and 1.90 times that of FP separator, respectively. Furthermore, Zn||MnO₂ batteries with FP-HOFs separator maintained a capacity retention of 57.2% after 350 charge/discharge cycles, significantly outperforming glass fiber (GF) with 1.3% and FP with 13.6%. The unique design of this Janus separator provides helpful guidance for low-cost, safe, and high-performance AZIBs.